How RISUG Works

Let's face it, females have a slew of choices when it comes to preventing pregnancy. There's the female condom, diaphragm, cervical cap, sponge and intrauterine device, as well as hormonal solutions, such as birth control pills, patches, implants and the vaginal ring. Men who want to share this burden, however, have far fewer options.

Men have used condoms made of various materials -- from animal intestines to latex -- for centuries as a barrier to prevent the escape of sperm into their partners' vaginas. They are 95 percent effective when used properly and remain one of the best solutions for preventing the spread of sexually transmitted infections. Unfortunately, they can break during intercourse or even slip off if the man using it is inexperienced. There's also withdrawal, of course, which can prevent pregnancy (but not sexually transmitted infections) and requires some skill on the user's end to be done properly.

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No wonder many men choose to get a vasectomy, a surgical procedure in which each vas deferens is cut and sealed off. Although successfully tested on animals in the mid-1800s, the surgery didn't see widespread use in humans until after World War II. Today, vasectomies account for only 5 percent of all contraception, despite being 100 percent effective [source: Alexander]. One major issue is the irreversibility of the procedure. Surgery can reconnect the vas deferens of a vasectomy patient, but it's expensive and works only about 40 percent of the time [source: Encyclopædia Britannica].

Hormone therapy could solve all of these problems, but comes with its own serious side effects. For example, the World Health Organization has run trials with men who receive twice weekly injections of testosterone. As noted earlier, this has the effect of suppressing sperm production by decreasing levels of GnRH, LH and FSH. WHO scientists got good results, but they found that the frequent injections posed a commercial and psychological barrier. More troubling, high levels of circulating testosterone led to increased irritability, acne and reduced levels of good cholesterol in many test subjects.

The holy grail in male contraception is an approach that requires no surgery or hormone suppression, yet delivers 100 percent effectiveness without permanent sterilization. The most promising techniques in recent years target the vas deferens. A few scientists have been experimenting with plugs made of the same silicone material found in artificial joints. The idea is to create a roadblock in the vas deferens, blocking the exit of sperm. When a man is ready to start a family, his physician simply removes the plug.

RISUG operates in a similar fashion, but with a few key differences, which we'll explore on the next page.